It is known to cover hot tubs or spas to prevent contamination due to environmental debris, such as leaves, pollens and the like, to prevent excessive evaporation when the spa is not in use and to act as a safety measure to prevent animals, small children and the like from falling into the water when unsupervised.
Most conventional spa covers are fabric covered foam structures which rest atop the spa when the spa is not in use and which are removed, either by sliding off the tub or by folding at a middle and lifting to a position away from the top of the tub, such by a support frame wherein the cover is suspended vertically in the folded position adjacent a side of the tub. The fabric covers may be susceptible to chemical vapors, such as chlorine, are prone to tearing at seams exposing the foam layers to the elements and to the steam and vapors from the tub and are generally susceptible to normal wear and tear necessitating multiple replacements during the life of the average spa.
It is known to provide fixed structures built around the hot tub to provide an element of protection for use during inclement weather or to prevent excessive exposure to the sun. Most often the structure is independent of the cover and remains in a fixed position around the tub, the roof portion being fixed above the spa to permit use of the spa. While these structures may meet the needs of the user by providing a rigid or semi rigid roof structure, they add additional expense by requiring a spa cover to be used as well.
Conventional spa covers are not designed to handle the weight of a person or persons resting on the cover. As the spa covers are typically flat however, individuals may be encourage to walk or otherwise provide undue weight on the cover, such as when shoveling snow from a deck in which the spa is recessed, which results in damage not only to the cover but to the spa itself.
Others have attempted to provide domed rigid or semi-rigid cover structures which, like the conventional cover, reside atop the spa when in use and which are pivoted or slid laterally away from the spa when the spa is to be used.
It is known to provide a vertically actuable cover to a swimming pool or a spa. U.S. Pat. No. 3,566,420 to Peterson et al teaches hydraulic actuators used to raise and lower a cover from a swimming pool and U.S. Pat. No. 6,718,566 to Wilson teaches a plurality of telescoping and threaded sections which are used to raise and lower a cover over a spa.
There remains interest in the industry to find reliable, relatively simple and inexpensive lift systems for raising and lowering roof structures over spas, which can act to replace a conventional spa cover when in a lowered, spa engaging position and which act as a roof when in the raised position.